Pipeline specifications for crude oil quality strictly limit the amount of certain sulfur containing components, such as mercaptans. Conventional sweetening treatments such as amine treating, caustic solution treatment, and proprietary processes, such as Merichem Company's NAPFININGSM, Exxon Mobil's SCANfiningSM, and the like are known to those skilled in the art. Some of the known proprietary processes use specialty solvents such as SELEXOL®, available from Union Carbide Corporation and licensed by UOP. These processes generally fall into two categories, extractive and non-extractive. Extractive processes generally use a solvent to remove sulfur-containing components, mercaptans for example, from the crude oil. The extracted mercaptans generally are reacted to form disulfides following removal from the crude oil. Non-extractive processes generally convert the mercaptans to disulfide oils which remain mixed with the crude oil. Correspondingly, hydrogen sulfide may be converted to sulfur. Disulfide oils which remain mixed with the crude oil affect the crude oil's value and hinders refining operations due to the additional, more complex processes needed to remove the disulfides from the resulting product streams. Crude oil containing disulfides also increase hydrogen requirements for refining and require more expensive metallurgy. Both extractive and non-extractive mercaptan removal processes are also used to remove sulfur and sulfur-containing species such as hydrogen sulfide and other organic sulfides, e.g., disulfides and thiophenes.
In remote production and hydrocarbon processing sites, infrastructure such as roads, railways and electrical supplies are not readily available. Thus, it is difficult to transport chemicals such as caustic, amines and specialty solvents to the site and power electrical equipment. Some sites are also located in environmentally sensitive areas such as regions containing permafrost. In these areas, it is undesirable to build additional infrastructure and increase the size of the areas (footprint) used to produce and/or process the hydrocarbons. Reduced use of chemicals save storage and further reduce the facility's footprint, but also increases safety for the environment and personnel. For crude petroleum offshore platforms, weight requirements may also be reduced. Cold climates also have freeze protection issues relating to any pipelines and equipment when using chemicals diluted with water, e.g., caustic solutions. Accordingly, the present invention offers an improvement to these processes. Therefore, the industry has sought a method and apparatus for removing sulfur-containing components from crude oil which reduce the need for infrastructure, reduce the area required for production, reduce the weight on production platforms, reduce potential freezing problems, provide improved safety and that are more environmentally friendly.